Characteristics of 18th century British built ships

by Ruffin
(Napa CA, USA)

I'm building a model ship kit of the CSS Alabama. When I started I realized that there were flaws of accuracy in some of the fittings so I began research. In Capt. Raphael Semmes "Memoirs of Service Afloat, During the War Between the States", he mentions one of his sailors who could identify a Yankee built ship while the hull was still below the horizon.
The method was that Yankee ships had square cut white sails and tapered mast and spars. The Alabama was built by Laird & sons at Brickenhead on the Mercy River. Since she was built to resemble a Brit merchantman. What color and cut would the sails have been and were the mast and spars have been squared or round.